A solid oxide fuel cell (“SOFC”) is known as high-efficiency fuel cell suitable for a wide range of uses. The SOFC is operated at elevated temperatures in order to increase ion conductivity, allowing air discharged from a compressor of a gas turbine to be used as air (oxidant) supplied to an air electrode side. The SOFC also allows high-temperature fuel that could not previously be utilized to be used as fuel for gas turbine combustors.
Thus, various power generation systems that combine an SOFC, gas turbines, and steam turbines to allow high-efficiency power generation to be achieved have been proposed, such as the system disclosed in Patent Document 1. The combined system disclosed in Patent Document 1 is provided with an SOFC, a gas turbine combustor for combusting exhaust fuel gas and exhaust air discharged from the SOFC, and a gas turbine comprising a compressor that compresses air and supplies the air to the SOFC.